1. Field of the Invention
The present invention related to printed circuit board assemblies and more particularly concerns an arrangement for sequentially engaging different connector parts on a single circuit board and an improved connector assembly.
2. Description of Related Art
In arrangements described in the above-identified co-pending applications, first and second stacks of parallel closely spaced circuit boards are directly connected to one another in a edge to edge relation. Each printed circuit board has an edge provided with a series of hermaphroditic connector nodes to enable circuit boards to be connected directly to one another in edge to edge relation. The two stacks of boards are mounted in a structural housing cage which carries an array of service cable connector receptacle parts, each one of which connects with a service cable connector plug part that is carried by an individual one of the printed circuit boards. The hermaphroditic connector nodes employ pressure type contact elements, sometimes called "contact dots", "bumps" or "buttons", providing an array of raised conductive dots on one connector node that is firmly pressed against a mating array of raised conductive dots on a mating connector node. This provides electrical signal contact and transmission of the data signals between the nodes and therefore between the printed circuit boards to which the nodes are mounted. However, for coupling of input/output signals and electrical power, each connector board includes a plurality of service cables connected to a service cable connector part, such as a plug, which is arranged to mate with a service cable receptacle part carried on the housing structure that mounts the circuit board stacks. Connections between the service cable connector parts require a significant degree of motion of the parts toward one another, and a greater amount of force, to fully engage the pin and socket type connections that are employed for power and input/out signals.
To interengage raised dots of the connector nodes, the boards are moved into position and pressed against one another by a camming lever before the connector elements of the service cable connector parts are engaged so as to avoid any misalignment forces on the raised dot connections caused by tolerances in dimensions of the parts. A screw and nut arrangement is provided on the service cable connector parts to pull these together and fully engage their pin and socket connector elements after the raised dot node pressure connections are made. However, since there is no further motion available for the printed circuit board itself after connection of the raised do connections of the connector nodes, it is imperative that the screw and nut securing elements of the service cable connector parts be so positioned on interengagement of the raised dot connector elements that mere rotation will threadedly interengage the screw and nut so as to pull the service cable connector parts together. The nut and screw must not be allowed to engage one another before completion of the pressure type contact of the raised dots or they might interfere with or prevent full pressure contact of the raised dots. To meet such rigorous requirements the parts must be made to very tight dimensional tolerances, which greatly increases cost of manufacture. Because of the difficulty of obtaining and maintaining such tolerances during repeated insertion and detachment of individual circuit board assemblies, reliability of circuit connections is significantly decreased.
Accordingly, it is an object of the present invention to provide for multiple connections that avoid or minimize above mentioned problems.